Electric convection heater



Oct 3, 1933 G. H. PHELPs ET Al.

ELECTRIC CONVECTION HEATER Filed Aug. 16, 1929 2 Sheets-Sheet 2 n Ue n for 56, YEoRcEfH/EL PJ.

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vPatented Oct 3, 1933 4m1131511 OFFICE v 1,929,178 liiLlioiln-Io ooNvEoT'IoN HEATER George H. Phelps, Warehouse Point, Conn., and l-Valentine E.- Walters, Erooklyn, N. Y., asi'sig'nols, by mesne assignments, to Metropolitan Engineering Company, a corporation of New York Application August 16,

v4 Claims.

lThis invention relates to electric heating apparatus and radiators and more particularly to apparatus in which the heating element is enclosed in a cabinet or enclosure having openings for the circulation of air.

In aheating element of the above type all ci" the electric energy supplied to the heater is converted into heat and if it is not transferred to and dissipated to the surrounding atmosphere with suicient rapidity will generate a temperature sufficiently high to cause a rapid oxidation and scalingof the exposed metal parts of the heating element or may keven result in a melting of the metal if a low melting point metal such as aluminum is used on the heater. The dissipation of heat into the air circulating through an enclosing structure ispromoted by the circulation of the air and may be very materially increased by the use of ns projecting into the circulating air current, but the use of an extensive fin structurehas the disadvantage that it increases the cost of the apparatus. The use of a limited or small finstructure, however, involves a danger of scorching the paint of the enclosure, in the event that any part of the fins come into close Contact with Vthe enclosure, inasmuch as fins of small area reach ay high temperature` An object of our invention is to provide a heating apparatus in which a rapid circulation of air and a rapid heat transferto the air Yare obtained with a minimum of heat dissipating or iin surface,without danger of scorching or discoloring the enclosing cabinet and without raising the metal ofthe heater in contact with the circulating air to a destructive temperature.

Other objects and features of the invention` are to provide a radiator of the type mentioned in which a very simple and effective fin structure is provided, and in which alow melting metal, such as aluminummay be used without danger of destruction and to provide a combined heating shell and iin structure of cheap and simple construction.

With these and other objects in view the invention comprises the radiator and heating apparatus described in the following specication and claims.

The various features of the invention are illustrated in the accompanying drawings, in which:

Fig. 1 is a side View of a heating cabinet and electric radiator embodying a preferred form of the invention;

Figs. 2 and 3 are respectively a plan and an end view of the heating apparatus shown in Fig. 1; Y

1929. Serial No. 386,245

Fig. 4 is a vertical section on an enlarged scale Y y of the apparatus taken on line 4 4 of Fig; 1;

Fig. 5 is a detail view of a part of the radiator and sectional view of a part of the cabinet or enclosure, and

Fig. 6 is a cross-sectional view of a modied form of heating element.

In the present invention an electric resistance heating element l0 of elongated form is mounted on a support l1 having spaced legs 12 and 13 and is placed within a cabinet or enclosure 14. The enclosure 14 is open at its lower end providing an inlet opening 15 and is provided at its top or upper end With a grid plate 16 having outlet openings 17 for the egress of heated air. The enclosure may be mounted on the legs 12 and 13 by means of bolts 18 thus forming a unitary structure with the heating element. When current is supplied'to the heater 10 and the heater is heated suiiiciently to warm or heat the air in contact with the heater the warm air rises upwardly and passes through the outlet openings 17 to be replacedby fresh air entering through the inlet 15. The quantity of heat absorbed by the circulating air increases with the circulation of the air, which, in turn is accelerated by a rise in temperature of the heater, and thus the tendency of the heater to rise in temperature is counteracted by the cooling action of the circulation of the air, which is stimulated with increasing temperatures of the heater, until a balance is reached.

The heater 10 is formed oi a coil 19 of electric resistance wire of a high resistance to high temperature and may extend from a terminal at one end of the heating element to a terminal at the other or, as indicated in the drawings, may extend in two or more lengths :from a terminal 2() at one end to the other endand then return to a terminal 2l, terminals may connect to a cable through a plug 22 of any suitable type. The resistance wire 19 is enclosed within a metal shell 23 and is electrically insulated therefrom by means of an insulating lling 24. When current is passed through the wire 19 the energy of the current is entirely transformed into heat which is conducted through the iilling 24 to the shell 23 from which it is transmitted to the air passing upwardly through the enclosure 14. The shell 23 is however heated by the current to a high temperature sufiicient to cause a rapid oxidation and scaling of such metals as copper and iron. A metal such as aluminum is therefore used as it resists such oxidation. The temperature of the aluminum may, however, be raised nearly to its fusion point. rIo guard against weakening of the metal at such high temperatures, the area of metal through which the heat may be transferred to the upwardly passing air is increased.

For this purpose the shell 23 is provided with an upwardly extending iin or vane 25 that eX- tends the length of the heater and with a downwardly extending longitudinal vane or fin 26, that is bolted between the two leg members of the stand 11 by bolts 27, thus serving to support the heater centrally of the enclosure 14, The fins 25 and 26 are heated by heat from the shell 24 lowering the temperature of the latter and transmitting this heat to the upwardly passing air current. To prevent the high temperature of the fins from being transmitted to the enclosure 14 and thus scorching or discoloring the paint on the latter the edges of the ns are spaced from the top of the enclosure as at 28 and from the ends as at 29 and 30 so that the walls of the enclosure are contacted only by the relatively colder upwardly owing air currents. To prevent the passage of suflicient heat to the support 11 and legs 12 and 13 and adjacent parts of the enclosure 14 to raise the latter to a high temperature sheets 31 of high temperature heat insulating material, such as mica, are inserted between the n 26 and the support 11.

The shell 24 and fins 25 and 26 may be formed in any suitable manner. In the preferred form of the invention, they are formed of a pair of plates having areas 32 and 33 of a flattened semicylindrical shape which, when placed in complementary position form the hollow shell 23 and broad areas that, when the areas 32 and 33 are in complementary relation form the fins 25 and 26 and narrower areas 34 and 35 that abut the n areas and are secured thereto by bolts 36 and 37, thus enabling the shell to be taken apart.

This construction also permits a single thickness of metal to be used for the fins thus economizing on the metal required for the iins. Or the plates may be permanently welded together by rivets 38 as in the modification shown in Fig. 6.

It will be understood that where the heating effect is not so great or a metal resistant to the effects of high temperatures is used the fins may be dispensed with, the heater being spaced from and heat insulated from the walls of the enclosure. Where iins are used the above construction provides a simple and easily constructed form of fin easily proportioned to any required conditions.

Having described the invention, what we claim and desire to secure by Letters Patent is:

1. In a hot air radiator, a casing having openings for the circulation of air therethrough, a heater assembly comprising an elongated heater element and a plate-like heat radiating shell enclosing said heater element and electrically insulated therefrom, and means to horizontally support said heater assembly within said casing. said means comprising two pairs of spaced support members, each pair having lower diverging sections adapted to form supporting legs and upper converging sections adapted to engage and support the said heater assembly, said upper sections terminating adjacent their ends in sections having abutting faces, thermal insulating material disposed adjacent each abutting tace and means to clamp said faces together with one of the plate elements of said heater assembly disposed therebetween.

2. In a hot air radiator including a casing having openings for the circulation of air therethrough, an elongated heater assembly comprising an elongated heater element and a plate-like heat radiating shell enclosing said heater element and electrically insulated therefrom, means to horizontally support the said assembly within the said casing, said means comprising two pairs of spaced support members, each pair having lower diverging sections adapted to form supporting legs and upper converging sections adapted to engage and support the said heater assembly, said upper sections terminating adjacent their ends in sections having abutting faces, thermal insulating material disposed adjacent each abutting face and means to clamp said faces together with one of the plate elements of said heater assembly disposed therebetween.

3. In a hot air radiator, heater element and radiator casing supporting means comprising two pairs of spaced supporting members, each pair having lower diverging sections adapted to serve as supporting legs and upper converging sections adapted to meet and serve as heater element supporting means, means to clamp said upper sections together and means to attach a radiator casing to the outer facesy of the said supporting legs.

4. A hot air radiator including a casing having a lower air inlet opening and an upper air outlet opening, an air heating assembly disposed within the said casing, said assembly comprising an elongated heater element enclosed by a plate-like heat radiating shell electrically insulated therefrom, and support means for said casing and heater assembly, said means comprising two pairs of spaced supporting members each pair having lower diverging sections adapted to serve as supporting legs and upper converging sections adapted to meet and serve as heater element supporting means, means to clamp said upper sections together and means to attach a radiator casing to the outer faces of the said supporting legs.

GEORGE H. PHELPS. VALENTINE E. WALTERS.

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